Re: [PATCH 1/1] mm: protect xa split stuff under lruvec->lru_lock during migration

From: Zhaoyang Huang
Date: Thu May 30 2024 - 05:00:25 EST

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In reply to: Yafang Shao: "Re: [PATCH 1/1] mm: protect xa split stuff under lruvec->lru_lock during migration"
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On Thu, May 30, 2024 at 4:49 PM Yafang Shao <laoar.shao@xxxxxxxxx> wrote:
>
> On Tue, May 21, 2024 at 3:42 AM Marcin Wanat <private@marcinwanatpl> wrote:
> >
> > On 15.04.2024 03:50, Zhaoyang Huang wrote:
> > > On Mon, Apr 15, 2024 at 8:09 AM Dave Chinner <david@fromorbitcom> > wrote: >> >> On Sat, Apr 13, 2024 at 10:01:27AM +0800, Zhaoyang
> > Huang wrote: >>> loop Dave, since he has ever helped set up an
> > reproducer in >>> https://lore.kernel.org/linux- >>>
> > mm/20221101071721.GV2703033@xxxxxxxxxxxxxxxxxxx/ @Dave Chinner , >>> I
> > would like to ask for your kindly help on if you can verify >>> this
> > patch on your environment if convenient. Thanks a lot. >> >> I don't
> > have the test environment from 18 months ago available any >> more.
> > Also, I haven't seen this problem since that specific test >>
> > environment tripped over the issue. Hence I don't have any way of >>
> > confirming that the problem is fixed, either, because first I'd >> have
> > to reproduce it... > Thanks for the information. I noticed that you
> > reported another soft > lockup which is related to xas_load since
> > NOV.2023. This patch is > supposed to be helpful for this. With regard
> > to the version timing, > this commit is actually a revert of <mm/thp:
> > narrow lru locking> > b6769834aac1d467fa1c71277d15688efcbb4d76 which is
> > merged before > v5.15. > > For saving your time, a brief description
> > below. IMO, b6769834aa > introduce a potential stall between freeze the
> > folio's refcnt and > store it back to 2, which have the
> > xas_load->folio_try_get_rcu loops > as livelock if it stalls the
> > lru_lock's holder. > > b6769834aa split_huge_page_to_list -
> > spin_lock(lru_lock) > xas_split(&xas, folio,order)
> > folio_refcnt_freeze(folio, 1 + > folio_nr_pages(folio0) +
> > spin_lock(lru_lock) xas_store(&xas, > offset++, head+i)
> > page_ref_add(head, 2) spin_unlock(lru_lock) > > Sorry in advance if the
> > above doesn't make sense, I am just a > developer who is also suffering
> > from this bug and trying to fix it
> > I am experiencing a similar error on dozens of hosts, with stack traces
> > that are all similar:
> >
> > [627163.727746] watchdog: BUG: soft lockup - CPU#77 stuck for 22s!
> > [file_get:953301]
> > [627163.727778] Modules linked in: xt_set ip_set_hash_net ip_set xt_CT
> > xt_conntrack nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nft_compat
> > nf_tables nfnetlink sr_mod cdrom rfkill vfat fat intel_rapl_msr
> > intel_rapl_common intel_uncore_frequency intel_uncore_frequency_common
> > isst_if_common skx_edac nfit libnvdimm x86_pkg_temp_thermal
> > intel_powerclamp coretemp ipmi_ssif kvm_intel kvm irqbypass mlx5_ib rapl
> > iTCO_wdt intel_cstate intel_pmc_bxt ib_uverbs iTCO_vendor_support
> > dell_smbios dcdbas i2c_i801 intel_uncore uas ses mei_me ib_core
> > dell_wmi_descriptor wmi_bmof pcspkr enclosure lpc_ich usb_storage
> > i2c_smbus acpi_ipmi mei intel_pch_thermal ipmi_si ipmi_devintf
> > ipmi_msghandler acpi_power_meter joydev tcp_bbr fuse xfs libcrc32c raid1
> > sd_mod sg mlx5_core crct10dif_pclmul crc32_pclmul crc32c_intel
> > polyval_clmulni mgag200 polyval_generic drm_kms_helper mlxfw
> > drm_shmem_helper ahci nvme mpt3sas tls libahci ghash_clmulni_intel
> > nvme_core psample drm igb t10_pi raid_class pci_hyperv_intf dca libata
> > scsi_transport_sas i2c_algo_bit wmi
> > [627163.727841] CPU: 77 PID: 953301 Comm: file_get Kdump: loaded
> > Tainted: G L 6.6.30.el9 #2
> > [627163.727844] Hardware name: Dell Inc. PowerEdge R740xd/08D89F, BIOS
> > 2.21.2 02/19/2024
> > [627163.727847] RIP: 0010:xas_descend+0x1b/0x70
> > [627163.727857] Code: 57 10 48 89 07 48 c1 e8 20 48 89 57 08 c3 cc 0f b6
> > 0e 48 8b 47 08 48 d3 e8 48 89 c1 83 e1 3f 89 c8 48 83 c0 04 48 8b 44 c6
> > 08 <48> 89 77 18 48 89 c2 83 e2 03 48 83 fa 02 74 0a 88 4f 12 c3 48 83
> > [627163.727859] RSP: 0018:ffffc90034a67978 EFLAGS: 00000206
> > [627163.727861] RAX: ffff888e4f971242 RBX: ffffc90034a67a98 RCX:
> > 0000000000000020
> > [627163.727863] RDX: 0000000000000002 RSI: ffff88a454546d80 RDI:
> > ffffc90034a67990
> > [627163.727865] RBP: fffffffffffffffe R08: fffffffffffffffe R09:
> > 0000000000008820
> > [627163.727867] R10: 0000000000008820 R11: 0000000000000000 R12:
> > ffffc90034a67a20
> > [627163.727868] R13: ffffc90034a67a18 R14: ffffea00873e8000 R15:
> > ffffc90034a67a18
> > [627163.727870] FS: 00007fc5e503b740(0000) GS:ffff88bfefd80000(0000)
> > knlGS:0000000000000000
> > [627163.727871] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [627163.727873] CR2: 000000005fb87b6e CR3: 00000022875e8006 CR4:
> > 00000000007706e0
> > [627163.727875] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> > 0000000000000000
> > [627163.727876] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
> > 0000000000000400
> > [627163.727878] PKRU: 55555554
> > [627163.727879] Call Trace:
> > [627163.727882] <IRQ>
> > [627163.727886] ? watchdog_timer_fn+0x22a/0x2a0
> > [627163.727892] ? softlockup_fn+0x70/0x70
> > [627163.727895] ? __hrtimer_run_queues+0x10f/0x2a0
> > [627163.727903] ? hrtimer_interrupt+0x106/0x240
> > [627163.727906] ? __sysvec_apic_timer_interrupt+0x68/0x170
> > [627163.727913] ? sysvec_apic_timer_interrupt+0x9d/0xd0
> > [627163.727917] </IRQ>
> > [627163.727918] <TASK>
> > [627163.727920] ? asm_sysvec_apic_timer_interrupt+0x16/0x20
> > [627163.727927] ? xas_descend+0x1b/0x70
> > [627163.727930] xas_load+0x2c/0x40
> > [627163.727933] xas_find+0x161/0x1a0
> > [627163.727937] find_get_entries+0x77/0x1d0
> > [627163.727944] truncate_inode_pages_range+0x244/0x3f0
> > [627163.727950] truncate_pagecache+0x44/0x60
> > [627163.727955] xfs_setattr_size+0x168/0x490 [xfs]
> > [627163.728074] xfs_vn_setattr+0x78/0x140 [xfs]
> > [627163.728153] notify_change+0x34f/0x4f0
> > [627163.728158] ? _raw_spin_lock+0x13/0x30
> > [627163.728165] ? do_truncate+0x80/0xd0
> > [627163.728169] do_truncate+0x80/0xd0
> > [627163.728172] do_open+0x2ce/0x400
> > [627163.728177] path_openat+0x10d/0x280
> > [627163.728181] do_filp_open+0xb2/0x150
> > [627163.728186] ? check_heap_object+0x34/0x190
> > [627163.728189] ? __check_object_size.part.0+0x5a/0x130
> > [627163.728194] do_sys_openat2+0x92/0xc0
> > [627163.728197] __x64_sys_openat+0x53/0x90
> > [627163.728200] do_syscall_64+0x35/0x80
> > [627163.728206] entry_SYSCALL_64_after_hwframe+0x4b/0xb5
> > [627163.728210] RIP: 0033:0x7fc5e493e7fb
> > [627163.728213] Code: 25 00 00 41 00 3d 00 00 41 00 74 4b 64 8b 04 25 18
> > 00 00 00 85 c0 75 67 44 89 e2 48 89 ee bf 9c ff ff ff b8 01 01 00 00 0f
> > 05 <48> 3d 00 f0 ff ff 0f 87 91 00 00 00 48 8b 54 24 28 64 48 2b 14 25
> > [627163.728215] RSP: 002b:00007ffdd4e300e0 EFLAGS: 00000246 ORIG_RAX:
> > 0000000000000101
> > [627163.728218] RAX: ffffffffffffffda RBX: 00007ffdd4e30180 RCX:
> > 00007fc5e493e7fb
> > [627163.728220] RDX: 0000000000000241 RSI: 00007ffdd4e30180 RDI:
> > 00000000ffffff9c
> > [627163.728221] RBP: 00007ffdd4e30180 R08: 00007fc5e4600040 R09:
> > 0000000000000001
> > [627163.728223] R10: 00000000000001b6 R11: 0000000000000246 R12:
> > 0000000000000241
> > [627163.728224] R13: 0000000000000000 R14: 00007fc5e4662fa8 R15:
> > 0000000000000000
> > [627163.728227] </TASK>
> >
> > I have around 50 hosts handling high I/O (each with 20Gbps+ uplinks
> > and multiple NVMe drives), running RockyLinux 8/9. The stock RHEL
> > kernel 8/9 is NOT affected, and the long-term kernel 5.15.X is NOT affected.
> > However, with long-term kernels 6.1.XX and 6.6.XX,
> > (tested at least 10 different versions), this lockup always appears
> > after 2-30 days, similar to the report in the original thread.
> > The more load (for example, copying a lot of local files while
> > serving 20Gbps traffic), the higher the chance that the bug will appear.
> >
> > I haven't been able to reproduce this during synthetic tests,
> > but it always occurs in production on 6.1.X and 6.6.X within 2-30 days.
>
> We encountered a similar issue several months ago. Some of our
> production servers crashed within days after deploying the 6.1.y
> stable kernel. The soft lock info as follows,
>
> [282879.612238] watchdog: BUG: soft lockup - CPU#65 stuck for 101s!
> [container-execu:1572375]
> [282879.612513] Modules linked in: ebtable_filter ebtables xt_DSCP
> iptable_mangle iptable_raw xt_CT cls_bpf sch_ingress raw_diag
> unix_diag tcp_diag udp_diag inet_diag iptable_filter bpfilter
> xt_conntrack nf_nat nf_conntrack_netlink nfnetlink nf_conntrack
> nf_defrag_ipv6 nf_defrag_ipv4 bpf_preload binfmt_misc cuse fuse
> overlay af_packet bonding intel_rapl_msr intel_rapl_common
> 64_edac kvm_amd kvm irqbypass crct10dif_pclmul crc32_pclmul
> polyval_clmulni polyval_generic ghash_clmulni_intel sha512_ssse3
> aesni_intel crypto_simd cryptd rapl pcspkr vfat fat xfs mlx5_ib(O)
> ib_uverbs(O) input_leds ib_core(O) sg ccp ptdma i2c_piix4 k10temp
> acpi_ipmi ipmi_si ipmi_devintf ipmi_msghandler acpi_cpufreq ip_tables
> ext4 mbcache crc32c_intel jbd2 mlx5_core(O) mlxfw(O) pci_hyperv_intf
> psample mlxdevm(O) mlx_compat(O) tls nvme ptp pps_core nvme_core
> sd_mod t10_pi ahci libahci libata
> [282879.612571] CPU: 65 PID: 1572375 Comm: container-execu Kdump:
> loaded Tainted: G W O L 6.1.38-rc3 #rc3.pdd
> [282879.612574] Hardware name: New H3C Technologies Co., Ltd. H3C
> UniServer R4950 G5/RS45M2C9S, BIOS 5.30 06/30/2021
> [282879.612576] RIP: 0010:xas_descend+0x18/0x80
> [282879.612583] Code: b6 e8 ec de 05 00 cc cc cc cc cc cc cc cc cc cc
> cc cc 0f b6 0e 48 8b 57 08 48 d3 ea 83 e2 3f 89 d0 48 83 c0 04 48 8b
> 44 c6 08 <48> 89 77 18 48 89 c1 83 e1 03 48 83 f9 02 75 08 48 3d fd 00
> 00 00
> [282879.612586] RSP: 0018:ffffad700b247c40 EFLAGS: 00000202
> [282879.612588] RAX: ffff91d247a75d8a RBX: fffffffffffffffe RCX:
> 0000000000000006
> [282879.612589] RDX: 0000000000000026 RSI: ffff91d473cb7b30 RDI:
> ffffad700b247c68
> [282879.612591] RBP: ffffad700b247c48 R08: 0000000000000003 R09:
> fffffffffffffffe
> [282879.612592] R10: 0000000000001990 R11: 0000000000000003 R12:
> ffffad700b247cf8
> [282879.612593] R13: ffffad700b247d70 R14: ffffad700b247cf8 R15:
> ffffdfcd2c778000
> [282879.612594] FS: 00007f5f576fb740(0000) GS:ffff922df0840000(0000)
> knlGS:0000000000000000
> [282879.612596] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [282879.612597] CR2: 00007fe797100600 CR3: 0000002b2468e000 CR4:
> 0000000000350ee0
> [282879.612599] Call Trace:
> [282879.612601] <IRQ>
> [282879.612605] ? show_regs.cold+0x1a/0x1f
> [282879.612610] ? watchdog_timer_fn+0x1c4/0x220
> [282879.612614] ? softlockup_fn+0x30/0x30
> [282879.612616] ? __hrtimer_run_queues+0xa2/0x2b0
> [282879.612620] ? hrtimer_interrupt+0x109/0x220
> [282879.612622] ? __sysvec_apic_timer_interrupt+0x5e/0x110
> [282879.612625] ? sysvec_apic_timer_interrupt+0x7b/0x90
> [282879.612629] </IRQ>
> [282879.612630] <TASK>
> [282879.612631] ? asm_sysvec_apic_timer_interrupt+0x1b/0x20
> [282879.612640] ? xas_descend+0x18/0x80
> [282879.612641] ? xas_load+0x35/0x40
> [282879.612643] xas_find+0x197/0x1d0
> [282879.612645] find_get_entries+0x6e/0x170
> [282879.612649] truncate_inode_pages_range+0x294/0x4c0
> [282879.612655] ? __xfs_trans_commit+0x13c/0x3e0 [xfs]
> [282879.612787] ? kvfree+0x2c/0x40
> [282879.612791] ? trace_hardirqs_off+0x36/0xf0
> [282879.612795] truncate_inode_pages_final+0x44/0x50
> [282879.612798] evict+0x177/0x190
> [282879.612802] iput.part.0+0x183/0x1e0
> [282879.612804] iput+0x1c/0x30
> [282879.612806] do_unlinkat+0x1c7/0x2c0
> [282879.612810] __x64_sys_unlinkat+0x38/0x70
> [282879.612812] do_syscall_64+0x38/0x90
> [282879.612815] entry_SYSCALL_64_after_hwframe+0x63/0xcd
> [282879.612818] RIP: 0033:0x7f5f56cf120d
> [282879.612827] Code: 69 5c 2d 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e
> 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 63 d2 48 63 ff b8 07 01 00
> 00 0f 05 <48> 3d 00 f0 ff ff 77 02 f3 c3 48 8b 15 32 5c 2d 00 f7 d8 64
> 89 02
> [282879.612828] RSP: 002b:00007fff30375c48 EFLAGS: 00000206 ORIG_RAX:
> 0000000000000107
> [282879.612830] RAX: ffffffffffffffda RBX: 0000000000000003 RCX:
> 00007f5f56cf120d
> [282879.612831] RDX: 0000000000000000 RSI: 0000000001640403 RDI:
> 0000000000000003
> [282879.612832] RBP: 0000000001640403 R08: 0000000000000000 R09:
> 0000000001640403
> [282879.612833] R10: 0000000000000100 R11: 0000000000000206 R12:
> 0000000000000003
> [282879.612834] R13: 000000000163c5c0 R14: 00007fff30375c80 R15:
> 0000000000000000
> [282879.612836] </TASK>
>
>
> Unfortunately, we couldn't reproduce the issue on our test servers. We
> worked around it by disabling CONFIG_XARRAY_MULTI. Since then, these
> production servers have been running smoothly for several months.
>
> > If anyone can provide a patch, I can test it on multiple machines
> > over the next few days.
It is highly appreciated that you could help to try below one which
works on my v6.6 based android. However, there is a hard lockup
reported on an ongoing regression test(not sure if caused by this
patch yet). Thank you!

mm/huge_memory.c | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 064fbd90822b..5899906c326a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2498,7 +2498,7 @@ static void __split_huge_page(struct page *page,
struct list_head *list,
{
struct folio *folio = page_folio(page);
struct page *head = &folio->page;
- struct lruvec *lruvec;
+ struct lruvec *lruvec = folio_lruvec(folio);
struct address_space *swap_cache = NULL;
unsigned long offset = 0;
unsigned int nr = thp_nr_pages(head);
@@ -2513,9 +2513,6 @@ static void __split_huge_page(struct page *page,
struct list_head *list,
xa_lock(&swap_cache->i_pages);
}

- /* lock lru list/PageCompound, ref frozen by page_ref_freeze */
- lruvec = folio_lruvec_lock(folio);
-
ClearPageHasHWPoisoned(head);

for (i = nr - 1; i >= 1; i--) {
@@ -2541,9 +2538,6 @@ static void __split_huge_page(struct page *page,
struct list_head *list,
}

ClearPageCompound(head);
- unlock_page_lruvec(lruvec);
- /* Caller disabled irqs, so they are still disabled here */
-
split_page_owner(head, nr);

/* See comment in __split_huge_page_tail() */
@@ -2560,7 +2554,6 @@ static void __split_huge_page(struct page *page,
struct list_head *list,
page_ref_add(head, 2);
xa_unlock(&head->mapping->i_pages);
}
- local_irq_enable();

if (nr_dropped)
shmem_uncharge(head->mapping->host, nr_dropped);
@@ -2631,6 +2624,7 @@ int split_huge_page_to_list(struct page *page,
struct list_head *list)
int extra_pins, ret;
pgoff_t end;
bool is_hzp;
+ struct lruvec *lruvec;

VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
@@ -2714,6 +2708,14 @@ int split_huge_page_to_list(struct page *page,
struct list_head *list)

/* block interrupt reentry in xa_lock and spinlock */
local_irq_disable();
+
+ /*
+ * take lruvec's lock before freeze the folio to prevent the folio
+ * remains in the page cache with refcnt == 0, which could lead to
+ * find_get_entry enters livelock by iterating the xarray.
+ */
+ lruvec = folio_lruvec_lock(folio);
+
if (mapping) {
/*
* Check if the folio is present in page cache.
@@ -2748,12 +2750,16 @@ int split_huge_page_to_list(struct page *page,
struct list_head *list)
}

__split_huge_page(page, list, end);

> >
>
>
> --
> Regards
> Yafang

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In reply to: Yafang Shao: "Re: [PATCH 1/1] mm: protect xa split stuff under lruvec->lru_lock during migration"
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